In a related art scanning probe microscope, a probe and a sample are brought into contact with each other with the use of a cantilever having the probe to detect an amount of deflection of the cantilever, and an amount of amplitude when the cantilever vibrates by a displacement detection mechanism using, for example, an optical lever system (a semiconductor laser is condensed on a cantilever back surface, and a change of a reflected light from the cantilever is detected by the amount of movement on a photodetector). As a result, the probe and the sample surface are relatively scanned by a horizontal fine transfer mechanism while controlling a distance between the probe and the sample surface by a vertical direction fine movement mechanism according to the attenuation of the amount of deflection or the amplitude, or an amount of variation in a phase or a resonance frequency. As a result, the shape and the physical property of the sample surface are measured.
In the measurement of the scanning probe microscope, for the purposes of 1) positioning a spot of a semiconductor laser on the cantilever when using the optical lever system, and 2) positioning a probe tip on a portion to be measured of the sample, there is frequently provided an optical microscope that can observe at the same time the cantilever and the laser spot of the optical lever system, and the cantilever and the sample surface.
In the related art scanning probe microscope, a length of the cantilever is about 50 μm to 500 μm, a scanning area normally has one side of 100 μm or smaller, and one side of 1 mm or smaller even in a specific application. For this reason, in order to achieve the above objects 1) and 2), a viewing field size of the optical microscope is normally set to an area having one side of about 100 μm to 2000 μm. The sample is locally observed by an objective lens having an optical axial orientation aligned to a substantially perpendicular direction to the sample surface immediately above or on a lower side of the sample surface. An observation image of the objective lens is focused on an image sensor such as a CCD or a CMOS, and is displayed on a display.
In the scanning probe microscope, a control device is provided separately from a unit, and an equipment such as a keyboard, a mouse, a joy stick, or a trackball is operated to perform a measurement while watching the display connected to the control device.
The size of the viewing field can be varied within the above-mentioned range through a technique such as replacement of an objective lens by a revolver, an optical zoom mechanism, or a digital zoom that enlarges an image on the display.
The observation of the sample surface is performed from a direction substantially perpendicular to the sample by bending the optical axis through a mirror, even when the optical axis of the objective lens is arranged obliquely to the sample surface due to the layout of the device.
In the optical laser spot adjustment, a two-axial transfer mechanism that can transfer the spot in a longitudinal direction and a width direction of the cantilever is provided. Also, in order to position the sample and the probe, there is provided a coarse transfer mechanism that relatively transfers the sample and the probe in a horizontal direction (X- and Y-directions) and a perpendicular direction (Z-direction) to the sample surface.
An optical microscope that observes between the probe tip and the sample surface may be used in combination with the optical microscope having the optical axis perpendicular to the sample surface for the following purposes. For example, the optical microscopes are used in combination when the probe and the sample are brought closer to each other by the coarse transfer mechanism in the Z-direction, so as to confirm a distance between the probe and the sample to prevent a collision between the probe and the sample while bringing the probe and the sample closer to each other at a high speed. Further, the optical microscopes are used in combination to observe a near-field spot on the sample surface being scattered by the probe tip of a scanning near-field microscope, which is one type of the scanning probe microscope. In this case, in order to observe the probe tip, the optical axis of the optical microscope is set at a shallow angle to the sample surface. The optical axis is set at the angle smaller than an angle formed between an edge of a side surface of the cantilever and the probe tip, as a result of which the probe tip can be observed without being shadowed by the cantilever.    [Patent Literature 1] JP-A-2006-23443    [Patent Literature 2] JP-A-2006-90715
An overall size of the sample observed by the scanning probe microscope is frequently 10 mm or more in diameter in commercial devices. Also, in a semiconductor field which is one of the typical applied fields of the scanning probe microscope, there are many cases in which an arbitrary place of the sample 2 to 12 inches in diameter is measured. Further, in recent years, large-sized liquid crystal panels are observed. Thus, for the large-sized samples, the viewing field is too narrow in the optical microscope for sample observation mounted in the related art scanning probe microscope, and which portion of the overall sample is being measured cannot be grasped on the display. For that reason, in related-art, a measurer moves in front of the unit and operates the respective coarse transfer mechanisms in the horizontal (XY) direction and the vertical (Z) direction by a joystick while visually confirming the sample and the cantilever on the unit to perform coarse positioning, until a portion to be measured of the sample and the cantilever can be seen in the viewing field of the microscope. Thereafter, the measurer performs local observation through the optical microscope image on the display to position the spot of the optical lever on the cantilever or to precisely position the probe and the portion to be measured of the sample.
Also, in the microscope for confirming a distance between the probe and the sample in a height direction, because observation is performed at the shallow angle to the sample surface, the positions of the probe and the sample in-plane cannot be grasped.
Further, because the scanning probe microscope brings the probe and the sample into contact with each other or closer to each other to perform the measurement, a disturbance such as vibration, sound, or wind can become a noise component of the measurement data. Also, when a displacement detection mechanism of the optical lever system is used, a light may become a noise source. For that reason, the unit needs to be placed on a vibration isolation table, and housed in a soundproof cover formed of a metal plate or a sound proof material, a windproof cover having a periphery surrounded by an arbitrary material, or a lightproof cover that shields a light to perform the measurement. When the unit is housed in the soundproof cover, the windproof cover, or the lightproof cover, the sample and the cantilever cannot be visually recognized from the external. Therefore, the measurer needs to move in front of the unit every time an observation place is changed, retreat the probe and the sample from each other by several hundred μm or more for the purpose of preventing the probe and the sample from being damaged by vibration, open the cover to position a measurement place while confirming the cantilever and the sample, again close the cover, precisely position the portion to be measured by the optical microscope, and bring the probe and the sample closer to each other to perform the measurement. In this case, it takes a very long time to start the measurement. The measurer needs to move his body from a front of the display, and needs to perform a very cumbersome work.
For example, it is conceivable that a part of the cover is formed of a glass window enabling visual observation. However, this configuration is not preferable because a soundproof performance of the glass portion is also degraded, and the costs are also increased. Also, the visibility in a part of the cover is lower than that when the overall cover is opened.
Further, in the scanning probe microscope, the measurement may be performed in a vacuum or a gas atmosphere. In this case, because a circumference of the unit is covered with a chamber or a globe box, an interior situation of the unit is hardly confirmed from the external. Therefore, there is a need to open the chamber or the globe box to open the atmosphere for each confirmation.